test: pass dtype directly to empty_like instead of casting

Author: cpcloud

numba_cuda/numba/cuda/tests/cudapy/test_math.py

@@ -238,7 +238,7 @@ def unary_template_uint64(self, func, npfunc, start=0, stop=50):
     def unary_template(self, func, npfunc, npdtype, nprestype, start, stop):
         nelem = 50
         A = np.linspace(start, stop, nelem, dtype=npdtype)
-        B = np.empty_like(A).astype(nprestype)
+        B = np.empty_like(A, dtype=nprestype)
         arytype = numpy_support.from_dtype(npdtype)[::1]
         restype = numpy_support.from_dtype(nprestype)[::1]
         cfunc = cuda.jit((arytype, restype))(func)